1. Field of the Invention
The present invention relates to a voice input support program, voice input support device, and voice input support method that assist inputting of voice under noisy environment.
2. Description of the Related Art
In recent years, voice input support devices are used in various scenes. For example, use of voice input support devices has resulted in practical utilization of a car navigation system that enables handsfree operation during driving.
If a noise level is higher than a predetermined threshold value when users are going to speak, a conventional technique relevant to the invention is, for example, a voice recognition device that does not perform voice recognition (see Patent Document 1: Jpn. Pat. Appln. Laid-Open Publication No. 2003-29785). Another example of relevant technique is a voice recognition device that can change a sound volume and quality in voice synthesis and change an acoustic model in voice recognition (see Patent Document 2: Jpn. Pat. Appln. Laid-Open Publication No. 2005-122042).
However, voice recognition devices often cause recognition errors and irritate users. A major factor causing recognition errors is influence of noise, such as driving noise. Even under equal environments, recognition error rates differ depending on loudness of users' voices. When recognition errors occur, users cannot find out why errors are occurring, recognition errors are repeated, and hence feel much stressed.
According to the technique of the Patent Document 2, users are notified of neither reasons why voice recognition has not been carried out nor how voice recognition can be carried out. Therefore, acceptance of voice recognition can be rejected again so that users feel more stressed. In this technique, a threshold value for noise levels is constant while noise levels that disable voice recognition differ depending on users.
Since users also cannot know how loud users had better speak, users can speak too loud or softly compared with a suitable sound volume. Even if an instruction such as “loud voice”, “normal voice”, or “low voice” is given to users, users individually speak at different levels of volumes.